PNO-V-86-052, on 860805,reactor Trip Initiated by Turbine Load Rejection When Control Valves Closed,Causing Insurge of Water Into Pressurizer.Cause Under Investigation

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PNO-V-86-052:on 860805,reactor Trip Initiated by Turbine Load Rejection When Control Valves Closed,Causing Insurge of Water Into Pressurizer.Cause Under Investigation
ML20205C574
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 08/05/1986
From: Caldwell C, Huey R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-86-052, PNO-V-86-52, NUDOCS 8608120373
Download: ML20205C574 (1)


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3 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-86-52 Date: 08/05/86 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by Region V staff on this date.

FACILITY: Southern California Edison Company Licensee Emergency Classification San Onofre Unit 1 Notification of Unusual Event DOCKET NO. 50-206 ~ Alert Site Area Emergency General Emergency XX Not Applicable

SUBJECT:

REACTOR TRIP FROM HIGH PRESSURIZER LEVEL At 0245 PDT on August 5, 1986, the reactor tripped from 87% power. The trip was initiated by a turbine load rejection when the turbine control valves went closed causing an insurge of water into the pressurizer. The reactor tripped on a high pressurizer level (50%) trip signal and a subsequent turbine trip followed. At the time, the steam dumps were in the pressure control mode since the Tave input circuit to the. steam dumps was inoperable. In addition, a pressurizer PORV opened briefly when primary system pressure reached 2190 psi and one or more steam generator safety valves opened.

The cause of the turbine control valve closure and load rejection is currently under investigation. All plant system functioned properly.

This information is current as of 1030 PDT, on August 5, 1986.

CONTACT: C. Caldwell R. Huey FTS 463-3733 (714) 492-2641,.

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Chairman Zech EDO NRR IE NMSS ADM:DMB Ccmm. PA OIA RES DOT:Trans Only Comm. Bernthal MPA AEOD Comm. Roberts ELD Comm. Asselstine Regions:

SECY INPO NSAC ACRS Licensee:

CA (Reactor Licensees) REGION V: FORM 211 PDR Resident Inspector __ (Revised 3/14/83) 8608120373 860805 ~~~

PDR I&E gh PNO-V-66-052 PDR /